Several types of gas filter cassette units are known. For instance in WO 9629138 the support frame comprises profile sections of a flexible material, preferably of a plastic material, wherein the leg members are hingedly interconnected with the frame web portion. The leg members are provided with locking means and are pivoted into a clamping engagement with each other, securing the filter bags between the clamped leg members. Carrier beams extend between oppositely positioned frame side pieces supporting the filter bags in the folds. Also WO99/36155 discloses a gas filter cassette unit having frame profiles that are articulately connected to each other so that when closed, they clamp the filter material between them. The support frame is provided with a plurality of rod-like means connecting two opposite supporting frame parts with each other, supporting the filter bags preventing them from collapsing in strong draught. The seam between two adjacent filter pockets extends along the entire length of the rod-like means and is clamped to the rod-like means by an elongated strip provided with spikes directed backwards.
A different type of gas filter cassette unit is disclosed in U.S. Pat. No. 6,451,079 wherein the assembly exhibits an outer frame of plastic material and several individual filter elements, each of which comprises an inner frame, arranged inside the outer frame. The outer frame is composed of opposing limb profiles, a base profile and a closing profile, each of which have an essentially U-shaped cross section. The filter elements are pushed into the U-shaped limb profiles of the outer frame and are connected to each other in a dust free manner.
WO2006/126937 discloses a pocket filter assembly comprising a frame structure having a number of filter pocket openings wherein each filter pocket has a pocket mouth sealingly secured in a corresponding filter pocket opening. The frame structure comprises an outer sub-frame and a corresponding inner sub-frame connected and locked to each other by means of locking elements at locking positions distributed along the opening portions of the subframes defining the filter pocket openings.
The main objective of the present invention is to provide a gas filter assembly that is inexpensive, easy to produce, assemble and mount. Yet it is important that the support frame is stable and that the filter pockets are firmly connected to the frame. A further object has been to provide a gas filter assembly comprising various types of material that can be easily separated to be subsequently subjected to destruction or recycling as required.